These 5-way test strips test for total chlorine, free available chlorine (FAC), calcium hardness, pH, and alkalinity. Accurate and instant, these test strips are the easiest way to test your pool or spa water. Simply dip in your pool water for one second and remove immediately. Then match the colors on the strip to the color chart. To keep your pool at its best, test at each end of the pool at least twice a week. Test your spa before each use. 50 strips per bottle.